1. Field of the Invention
The present invention relates to an image taking apparatus that generates image data according to image taking operation and that includes an imaging device generating image data by reading a subject image formed on an imaging surface and an image taking optical system forming subject light on the imaging surface.
2. Description of the Related Art
Typically, a diaphragm, an ND filter and the like for adjusting the amount of subject light according to ambient lighting conditions are provided in an image taking apparatus that includes an image taking optical system forming subject light on an imaging surface and generates image data according to image taking operation. Such a diaphragm is, for example, arranged by inserting a plate with an opening such that the opening may be positioned around an optical axis to enable light-amount adjustment. Another example of such a diaphragm is obtained by defining an opening by plural aperture blades surrounding an optical axis and by significantly changing the magnitude of the opening to control the amount of light passing the optical axis. Alternatively, the typical ND filter is used by being inserted into the optical axis so as to attenuate the amount of light passing therethrough. With the aid of such light-amount adjusting tools, a user can perform shooting according to ambient light conditions to obtain favorable high-quality still image data.
Some image taking apparatuses have movie shooting function, and thus, aided by the light-amount adjusting tools, a user can also obtain favorable high-quality movie image data.
Here, it should be noted that, in a typical movie shooting, voice data is recorded with movie image data.
However, mechanic sounds generated when driving the aperture blades and the ND filter sometimes happen to be recorded via a microphone disposed in the image taking apparatus.
Such mechanic sounds are unwanted for a user and thus it is desirable to suppress such sounds.
Meanwhile, light-adjustment glass is proposed as a tool to adjust the transmitted amount of light (see, for example, Japanese Patent Application Publication No. 2001-83554).
The light-adjustment glass disclosed in Japanese Patent Application Publication No. 2001-83554 is formed by polymer gel particles including light-absorbing pigments and a solvent sandwiched between the surfaces of the glass. The polymer gel particles reversibly expand and contract by absorbing and releasing the solvent in response to change in temperature, and thus unit area of photo-reactive pigments changes to control the transmitted amount of light. Accordingly, such light-adjustment glass can control the transmitted amount of light by expansion and contraction of polymer gel particles without generating mechanic sounds.
Thus, it is expected that use of such light-adjustment glass in an image taking apparatus as a light-amount control tool may enable control of the transmitted amount of light without generating mechanic sounds.
However, as the light-adjustment glass disclosed in Japanese Patent Application Publication No. 2001-83554 is based on temperature change, a temperature-control device needs to be disposed in an image taking apparatus, which raises a problem in terms of cost and size of the apparatus. Accordingly, it is not desirable to use the light-adjustment glass as a light-amount adjustment tool of an image taking apparatus.